1. Field of the Invention
The invention relates to an antenna and in particular to a broadband antenna.
2. Description of the Prior Art
As the wireless telecommunication develops with the trend of micro-sized mobile communication product, the location and the space arranged for antennas are limited. Therefore, some built-in micro antennas have been used. Currently, some micro antennas such as a chip antenna, a planar antenna, and so on are commonly used. All these antennas have the feature of small volume. For example, a common chip antenna applying LTCC technology is known as a ceramic chip antenna. Additionally, planar antennas are also designed in many types such as a microstrip antenna, a printed antenna, and a Planar Inverted F Antenna. These antennas are applied widely to GSM, DCS, UMTS, WLAN, Bluetooth, etc. Despite the above antennas meeting the need of micro size, bandwidth will be insufficient. Under the circumstance, when the human body approaches the antenna, the antenna will be interfered with by inducing a frequency bias. Then, performance of the antenna will get worse and eventually malfunction.
To receive all kinds of frequencies, many antennas with different frequency are connected to a portable device. However, as the portable device is getting smaller along with the fact that other components limit the space of the antenna, the difficulty of antenna design inevitably increases. Besides, when the antenna is arranged, the shutter effect of human body may cause frequency bias of the antenna, further weakening the radiation effects of the antenna.
Therefore, an antenna structure design meeting the needs of increasing bandwidth, decreasing the shutter effect of human body, and not affecting the radiation effect is an important issue.